1. Field of the Invention
The present invention relates to an ink supply system, which is typified by an ink jet recording apparatus, and an ink cartridge.
2. Description of Related Art
Heretofore, the so-called pit-in (pit-stop) ink supply method has been known as one of methods for supplying ink to a liquid discharge head (ink jet head). In the pit-in ink supply method, there are provided a liquid storage container (sub-tank) for supplying a liquid to the liquid discharge head, and a liquid replenishing container (ink cartridge serving as a main tank) for replenishing the liquid storage container (sub-tank) with the liquid. A head cartridge, on which the sub-tank and the ink jet head are integrally mounted, is mounted on a carriage. Then, the carriage is moved to a predetermined position, in which a liquid supply member that is provided in a portion of the sub-tank is made to be connected to the liquid replenishing container (ink cartridge), so that the sub-tank is replenished with the liquid.
For the replenishment with ink using the pit-in ink supply method, it becomes necessary to have such an arrangement as to replenish the liquid storage container with a predetermined amount of ink neither too much nor too little. Accordingly, it becomes necessary to properly connect the liquid supply member that is provided in a portion of the liquid storage container to the liquid replenishing container (ink cartridge). Moreover, since the replenishment of the liquid storage container with ink is performed a number of times depending on the consumption of ink, the reliability and durability to be obtained when the liquid supply member that is provided in a portion of the liquid storage container is connected to the liquid replenishing container (ink cartridge) become important. Furthermore, in order to maximize the reliability obtained after the completion of such a connection, it is necessary to connect the liquid supply member that is provided in a portion of the liquid storage container to a predetermined supply portion of the ink cartridge with high precision.
Therefore, in Japanese Laid-Open Patent Application No. Hei 01-141750, there is disclosed, as one of commonly-used connection methods, an ink jet recording apparatus in which a part of the ink cartridge is provided with a protruding portion or portions for guiding the ink cartridge. The ink cartridge is locked and positioned relative to the ink jet recording apparatus by means of the protruding portion or portions.
In addition, in U.S. Pat. No. 5,541,631, there is disclosed an ink supply system in which a claw portion is provided on the surface of the ink supply port of an ink cartridge and a mounting portion for engagement with the claw portion is provided in an ink jet recording apparatus, and a projection of the claw portion serves to prevent the ink cartridge from being inserted into the main body of the ink jet recording apparatus in an erroneous manner and also serves as a latch for opening and closing of a cover of the ink jet recording apparatus when the ink cartridge is inserted.
Furthermore, in Japanese Laid-Open Patent Application No. 2000-127444, there is disclosed an ink supply system in which a positioning pin is provided on an ink cartridge and a positioning hole corresponding to the positioning pin is provided on the side of a holder for the ink cartridge, so that the precision of connection in the ink supply portion can be assured with the engagement between the positioning pin and the positioning hole.
In addition, for example, in U.S. Pat. No. 5,523,780, there is disclosed an ink supply system in which a positioning pin and an ink supply pipe are fixedly held at an interval and a mechanism for making a positioning-pin receiving portion and an ink-supply-pipe coupling portion integrally slidable relative to the positioning pin and the ink supply pipe is provided, so that the sliding portion is displaced in response to the coupling between the ink cartridge and the ink jet recording apparatus so as to perform positioning. There is also disclosed another ink supply system in which, conversely, the positioning-pin receiving portion and the ink-supply-pipe coupling portion are fixed and a mechanism for making the positioning pin and the ink supply pipe integrally slidable relative to the positioning-pin receiving portion and the ink-supply-pipe coupling portion is provided, so that the sliding portion is displaced in response to the coupling between the ink cartridge and the ink jet recording apparatus so as to perform positioning.
The ink cartridge positioning methods disclosed in the above-mentioned examples of prior art can be said to have been devised on the premise that an ink cartridge would be loaded into the ink jet recording apparatus only once or several times by an ordinary user. However, in cases where the replenishment of the sub-tank with ink is performed with the action of connecting the liquid supply member that is provided in a portion of the sub-tank to the liquid replenishing container (ink cartridge), as described in the foregoing, the sub-tank will be replenished with ink a plurality of times depending on the consumption of ink, and there is a probability that the replenishment of the sub-tank with ink will be performed several tens of times to several hundred times due to the use of a high-capacity ink cartridge. Therefore, there are required the high reliability and high durability in long-term use to be obtained when the liquid supply member that is provided in a portion of the liquid storage container is connected to the liquid replenishing container (ink cartridge).
In addition, on the other hand, in recent ink jet recording apparatuses, compatibility with color recording has been advancing, and such a type of ink jet recording apparatus that forms a color image by superimposing droplets by means of a plurality of color ink jet heads has come into wide use. In general, in color recording, there are three or four kinds of ink jet heads and ink cartridges corresponding to three primary colors, i.e., yellow (Y), magenta (M) and cyan (C), or four colors including black (B) in addition to the three primary colors.
In these days, ink jet recording apparatuses having ink jet heads for three or four colors mounted thereon to form a color image have been in practical use. Also, ink jet recording apparatuses capable of forming a high-definition image with photographic accuracy through the use of inks of six colors including light magenta (LM) and light cyan (LC) in addition to the above-mentioned four colors have been in practical use.
Accordingly, ink storage containers for inks of a plurality of colors come to be included in a single ink cartridge, and, therefore, it becomes necessary to perform ink replenishment (connection or coupling) individually for each color.
However, if a claw or pin such as that disclosed in the above-mentioned examples of prior art is provided in each of the connection portions for inks of a plurality of colors, an ink cartridge would increase in size.
Furthermore, in the embodiments disclosed in U.S. Pat. No. 5,523,780, since the sliding mechanism is provided on the side of the ink supply pipe or, conversely, on the side of the ink-supply-pipe coupling portion, an ink cartridge would tend to increase in size. Also, in cases where inks of a plurality of colors are used with the ink supply system having such a sliding mechanism, the sliding mechanism is required to be provided for each of coupled portions between the ink supply pipe and the ink-supply-pipe coupling portion for inks of a plurality of colors, so that such an ink supply system can not be said to be adapted to a small-sized printer. Further, in the case of a printer in which the ink replenishment (connection or coupling) is assumed to be performed a great number of times (several tens of times to several hundred times), there is a possibility that the sliding mechanism itself might deteriorate, so that it becomes necessary to improve durability of the sliding mechanism.
On the other hand, if, in order to prevent the ink cartridge from increasing in size, a single claw or pin is used to perform positioning of a plurality of coupled portions, it becomes difficult to absorb variations in the coupled portions, so that the precision of connection or coupling would diminish. Further, there is a probability that, as the precision of positioning lowers, surplus ink occurring at the time of connection or coupling will remain in the ink supply portion or the like of the ink cartridge. Such surplus ink will accumulate gradually according to the repetition of the above-mentioned connecting or coupling operation and then will spread over the ink supply portion, so that there is a possibility that inks of different colors will be mixed to cause a phenomenon of color mixture.
If the mixed inks of different colors are accidentally loaded into the liquid supply member that is provided in a portion of the sub-tank, the color of ink as discharged would vary, thereby lowering image quality and hindering the reliability of recording from being assured.